Q: Miss fire p0304, p0316

Hi there. An oil leak can definitely add to a misfire concern and needs to be addressed as well as the spark plugs that are oil soaked to determine if they compromised. A flashing check engine light is telling us that the catalytic converter will be damaged with continued operation. Have you swapped spark plugs then ignition coils to see if the misfire moves cylinders; if it moves with the spark plug then it’s the plug at fault and the same for the coil. There could be an injector failing or a mechanical concern that will require proper testing. I suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a check engine light inspection and a valve cover gasket service.